Method and apparatus for automatic load-balancing on multisegment devices

ABSTRACT

Automatic load-balancing provides a decision-making process that includes intelligent automatic detection of when a given load-balancing activation currently would not be beneficial, thereby keeping the user&#39;s network from being unnecessarily disturbed when no real benefit would be gained; a process to undo a prior load-balancing that can be activated when users have accidentally selected a feature which could substantially change their network configurations; and an extensive intelligent port-distribution algorithm that improves the network load by moving the right ports to new segments.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of application Ser. No. 08/738,940,filed Oct. 24, 1996, now U.S. Pat. No. 6,345,041, which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention relates to electronic communications networks. Moreparticularly, the invention relates to the automatic configuration ofhardware and software networking products for network segmentation tobalance the flow of communications and data between nodes on suchnetworks.

2. Description of the Prior Art

A network segment consists of repeaters, end stations, and connectivitybetween the stations (for example, see standard ISO/IEC 8802-3 forinformation on Ethernet networks). A set of predefined rules forcommunicating, called “protocols,” determines how and when end-nodes onthe network segment are allowed to communicate with one another, andwhat form such communication takes.

In a data communications network, data are transferred in the form ofpackets which contain the address of the sending station (the sourceaddress) and the address of the intended recipient (the destinationaddress). The exact packet format, and the predefined rules forinterpreting the contents of such packets, are again specific to thenetwork type and are made up of several levels of protocols. Asdescribed herein, a network segment has the capacity to transfer alimited amount of data per second. When more than the maximum mediaspeed of network data transfer capacity is required, multiple segmentscan be used. These segments can be interconnected through the use ofbridges or other packet-forwarding devices, which allow communicationbetween different segments (bridges are defined in standard ISO/IEC10038).

The term switch has recently been applied to bridges. Switches are fastbridges which generally do not use a CPU to process the packets. Bridgescontain two or more ports, each of which connects to a segment. When twostations on different segments communicate with each other, the bridgeforwards the packets between the two segments. When the stations are onthe same segment, the bridge does not forward the packets to any othersegment. The bridge may buffer data received on its ports to allowforwarding of the data later onto a different segment that was busy whenthe transmission first occurred.

Over time, a network may grow as more users (end-nodes) are added. Eachof these new end-nodes must then compete with existing end-nodes foraccess to the network. As the number of end-nodes which mightpotentially access the network medium grows, it becomes statisticallymore likely that the medium is in use when a given end-node wants totransmit, thereby requiring the end-node to wait. In addition, availablenetwork resources may be constrained when just a few end-nodes haveheavy resource impact. Nodes which transmit a lot of packets, whichtransmit a lot of broadcast or multicast packets (received by all ormany stations), or which create a lot of network disruptions (e.g.,collisions, late collisions, etc.), consume a lot of the availablenetwork resources, leaving less for other end-nodes. Thus, schemes whichincrease the amount of network resources available (i.e. the amount ofpotential accessibility to the network medium), without changing thetype of physical network used (preserving the users' investment), are ofgreat use and interest.

When the network medium is shared (as opposed to switched), one way ofincreasing the amount of available network resources is to split theshared medium into multiple segments (i.e., segment the network). Thislimits the number of users who have access to any one of these segments.If it is desired to have end-nodes in a segment communicate withend-nodes in other segments, bridging or switching or routing across thesegments may be employed, so that network packets for devices that arenot in the immediate segment are forwarded until they reach the segmentof the destination end-node.

While segmenting the network medium can improve resource availability,the choice of where to segment, e.g., which nodes should be assigned towhich segment, affects the success of the results. If all of the nodeswhich impact network resources the most remain on the same segment,access for any one of those nodes is not much improved by this scheme,while the less resource-impacting nodes on other segments have greatlyincreased opportunity for access but far less need of it. In thissituation, the increased resources are wasted on the wrong end-nodes.

Additionally, network systems are inherently complex. A significantamount of technical education is required to understand, configure, andmaintain any particular type of physical network, e.g. 10Base-T,Ethernet, Token Ring, or FDDI networks. As the use of networks becomeswidespread, the number of users responsible for such networks grows,while those among them who have sufficient knowledge to accomplish thesetasks declines. Thus, schemes which can configure, maintain, or improvenetwork conditions without requiring much specific knowledge on the partof the user are also of great use and interest. Such ease-of-use, i.e.user-friendly, schemes are often encompassed in software which is eitherembedded in network devices or external to them. These softwareapplications generally are known as intelligent network agents.

One network products vendor is presently marketing a 10Base-T networkswitch that allows any of its ports to be assigned to any one of fourinternal backplane segments. The product is described as having aload-balancing feature which can be activated in one of several ways:

-   -   On-demand by the user (i.e. a manual trigger);    -   At a designated time or interval; or    -   When a user-defined threshold is reached (this is a threshold of        a network value defined in the product's Management Information        Base (MIB) and configured via the Simple Network Management        Protocol (SNMP). For example, the MIB value could be a collision        count, a segment utilization pattern, or a switch utilization        pattern.

These mechanisms for triggering such actions are not new. The first twohave existed in practice for some time, and the third is an aspect ofrecent implementations of the Remote MONitoring (RMON) suite offeatures. The algorithms that are actually used by the product'sload-balancing feature to determine which ports to place on which of thefour internal backplane segments have been informally described as beingbased on end-node communication patterns gleaned from address-pairinformation in the switch's address table. Thus, this approach requiresthat the switching fabric and intelligent network agent components arefully integrated into the intelligent agent's hardware environment.

Accordingly, the state of the art provides an automatic load-balancingsolution that does not accommodate an inability on the part of the useror agent to communicate with the switching fabric (e.g.,packet-forwarding, address table, etc.) hardware. This arrangement has amajor disadvantage in that it is unusable with switches and otherpacket-forwarding devices which are fully external to the intelligentagent's hardware environment. It would therefore be advantageous toprovide an agent that can intelligently improve network resourceavailability, without requiring special, integrated packet-forwardinghardware.

In addition, the prior method may result in unnecessary load-balancing.It would therefore be advantageous to reduce network disruption byperforming such load-balancing only when it actually improves networkresource availability.

Furthermore, it is advantageous to provide an agent that canintelligently improve network resource availability while requiring onlya simple activate action on the part of the user, such that no furtheraction or special knowledge of the agent, its environment, or networksin general (such as how to set a threshold level, or even whichthreshold values would be meaningful) is required on the part of theuser.

SUMMARY OF THE INVENTION

The invention provides an intelligent network agent that implements afeature referred to as automatic load-balancing. The invention addressesboth of the major issues of network resource impact and ease-of-usedescribed above, and intelligently improves network throughput, whilerequiring only a simple activate action on the part of the user suchthat no further action or special knowledge of the agent, itsenvironment, or networks in general is required on the part of the user.The invention is designed to minimize network disruption byload-balancing only when it actually improves the network resourceavailability. Furthermore, because of the ability to use this inventionin environments where packet-forwarding support hardware is external tothe agent's environment, the invention works in situations where priorinventions do not, including cases where an external switch or otherpacket-forwarding device is manufactured by another vendor.

The automatic load-balancing method and apparatus further comprisesthree major components:

-   -   A decision-making process for automatically determining when a        given load-balancing activation currently would not be        beneficial;    -   An intelligent load-balancing port-distribution algorithm for        assigning ports to segments; and    -   A feature which allows undoing a prior load-balancing.

One goal for an intelligent feature of any sort involves determiningwhen to actually implement the feature. The herein disclosed automaticload-balancing invention checks for situations in which a givenautomatic load-balancing activation should not occur by weighing thepotential benefit of the action against its consequences, and by makingan intelligent decision for the user while preventing needless networkdisruption.

Automatic load-balancing moves end-nodes (or groups of end-nodes) afterthe system has been running to increase the overall throughput of thenetwork. This aspect of the invention redistributes hub ports tosegments with the goal of evenly balancing resource load across all ofthe known segments. Past history is used to anticipate the future load,i.e. history since either activation of the intelligent agent or sincethe last time the load-balancing feature itself was activated.

The feature to undo a prior load-balancing takes information stored at aprior load-balancing activation and uses it to return ports to theprevious configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block schematic diagram of an electronic communicationsnetwork;

FIG. 2 is a block schematic diagram of a preferred hardware environmentaccording to the invention;

FIG. 3 is a block schematic diagram of an apparatus for automatic loadbalancing on segmented devices according to the invention; and

FIGS. 4A and 4B are flow diagrams showing a preferred implementation ofan intelligent port distribution algorithm according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a block schematic representation of a typical electroniccommunications network, such as an Ethernet network. The network 10consists of several Local Area Networks (LANs) 12–16, each of which isinterconnected through a number of bridges 17–21. Each LAN is connectedto one or more bridges. Connection between a LAN and a bridge is througha port. For example, ports 211, 212, 213 are shown in connection withthe bridge 21. The principle functions of the bridge are to relay andfilter data frames, maintain the information required to make framefiltering and relaying decisions, and management of the foregoingoperations. Although the preferred embodiment of the invention isdiscussed in connection with an Ethernet network, the invention canreadily operate with networks other than Ethernet networks. In fact, theinvention herein described can apply at least to FDDI, as well as any ofthe networks specified in the IEEE 802 family of networking standards(e.g. 802.3 and 802.5).

The invention relates to the automatic configuration of hardware andsoftware networking products for network segmentation, e.g. with regardto balancing the flow of communications and data between nodes onnetwork segments to obtain more throughput on the network. Suchautomatic configuration off-loads responsibility for the management ofthe network and network devices from the system administrator, therebysaving time and training. Automatic configuration as disclosed hereinrefers to a decision made by the load balancing system including,potentially, an out-of-the-box first plug-in decision, and anyadjustment to the network devices after the network system is in use(e.g. a “find new load-distribution,” “set daytime config,” or a “setoff-hours config” decision).

FIG. 2 is a block schematic diagram of a preferred hardware environmentaccording to the invention. The hardware environment consists of anetwork hub 34 (or connected stack of hubs 35, 36, 37), a networkmanagement card 30 which contains the processor and firmware requiredfor the intelligent network agent features described herein, and anoptional internal packet-forwarding module 32 or externalpacket-forwarding module 38 required to maintain communication acrossall four of the hub stack's internal segments 1 . . . M.

The preferred packet-forwarding module 32 is integrated into the systemonly insofar as the module itself can be detected by the intelligentnetwork agent 30. The hub 34 (or connected stack of hubs 35, 36, 37) hasbackplane connections 1 . . . a, (a+1) . . . b, (y+1) . . . z which linkthe external ports 1 . . . a, (a+1) . . . b, (y+1) . . . z to any one ofthe hub stack's backplane segments 1 . . . M. The agent and thepacket-forwarding module's backplane connections tie directly into thehub stack's backplane segments 1 . . . M in the preferred embodiment ofthe invention. Other implementations of the invention can be appliedwherein a fully external packet forwarding module 38 connects toexternal hub ports, e.g. 1 . . . a, of which each hub port lies on adifferent backplane segment 1 . . . Q. These other implementationsmerely require information to be given to the intelligent agent, notingwhich ports on which of the devices in the agent's hardware environmentare connected to the packet-forwarding device(s). That information couldbe provided by other internal or external software mechanisms (e.g.management application topology information, messaging from a managementapplication, or an automatic switch detection module internal to theagent), or by user input (e.g. configuration via a simple managementinterface).

In the presently preferred embodiment of the invention, the packetforwarding module 32 is not tightly integrated into the system, in thatthe intelligent agent cannot control or communicate with the module'sswitching fabric (e.g. packet-forwarding or address table) hardware.Thus, the herein-disclosed automatic load-balancing method and apparatuspreferably accommodates the inability of a system user or theintelligent network agent to communicate with the packet-forwardingsupport hardware. This feature of the invention provides at least onemajor advantage over prior art approaches in that the invention is alsousable with switches and other packet-forwarding devices which are fullyexternal to the intelligent agent's hardware environment (includingswitches, bridges, or routers made by other vendors), or which are notmanageable by users, such as network administrators. The invention mayalso be used with an external software application rather than inside anembedded software agent.

FIG. 3 is a block schematic diagram of an apparatus for automatic loadbalancing on segmented devices according to the invention. The automaticload-balancing method and apparatus further comprise three majorcomponents:

-   -   A decision-making process 40 for automatically detecting when a        given load-balancing activation currently would not be        beneficial;    -   An intelligent load-balancing port-distribution algorithm 41 for        assigning ports to segments; and    -   An undo prior load-balancing feature 42 responsive to an undo        command 43 issued by a user.

For network communications between all nodes to be preserved, a meansfor forwarding packets between the segments (e.g. a bridge, a switch ora router) must be present and enabled for the automatic load-balancingfeature to be useful for the user.

Automatic Determination of when a Given Load-Balancing Activation wouldnot be Beneficial

One goal for an intelligent feature of any sort involves determiningwhen to actually implement the feature. The herein disclosed automaticload-balancing invention checks for situations in which a givenautomatic load-balancing activation should not occur. Such situationsinclude, for example, when the current load distribution is already goodenough or when current network resource impact is so low that no realproblems exist. This automatic determination of when a given instance offeature activation is not beneficial aspect of the automaticload-balancing invention weighs the potential benefit of the actionagainst its consequences, and makes an intelligent decision for the userwhile preventing needless network disruption.

Intelligent Port-Distribution Algorithm

Automatic load-balancing moves end-nodes (or groups of end-nodes) afterthe system has been running to increase the overall throughput of thenetwork. This aspect of the invention redistributes hub ports tosegments with the goal of evenly balancing resource load across all ofthe known segments. Past history is used to anticipate the future load,i.e. history since either activation of the intelligent agent or sincethe last time the load-balancing feature itself was activated. Thehistory can consist of the utilization on each port, communicationspatterns on the port, communications patterns on the segments, HP EASEdata, RMON data, sampling data, or other intelligent considerations.Using the past history, this aspect of the invention moves ports todifferent segments to try to achieve the same network resource impact onall segments as much as possible or necessary. It should be appreciatedthat the load-balancing features in general could be applied to anynumber of segments, although four segments are used in the preferredembodiment of the invention. Additionally, the load-balancing featurescould also be implemented by an external software application ratherthan the embedded intelligent agent described in this embodiment.

A number of intelligent decisions, including which ports are to bemoved, are incorporated into achieving a new load-balancingdistribution. Many of these decisions further the goal of minimizing thenumber of ports moved from their current segment to a new segment. Thisis because such an action may cause a temporary disruption to anyconversations which may be occurring between one or more of the movedend-nodes. These conversations occur at Open Systems Interconnection(OSI) layers higher than those with which hubs and switches concernthemselves. The provision of a good distribution while minimizing theunnecessary moving of ports is one unique feature of the invention. Theintelligent port distribution algorithm strives to achieve a very goodnetwork resource distribution across all segments while moving as fewports as possible. This feature of the invention includes assuring thatall of the top resource-impacting end-nodes, i.e. the greatest users ofthe available network resources, are distributed across differentsegments. In addition, it accommodates situations where a particularsegment may not be a good location upon which to place a particularport, i.e. it may not be fully qualified (e.g. when that segment isisolated from the multi-segment backplane on the device on which theport resides), and situations where the port should not be moved (e.g.when an external packet-forwarding device is connected to the port, orwhen a user or management application has designated the port not to bemoved).

The herein disclosed algorithm first collects a snapshot of informationabout all of the ports to be considered for redistribution(automatically excluding ports which should not be moved). Thisinformation could include many network resource attributes (e.g.utilization, packets, broadcast/multicast packets, collisions, latecollisions, etc.), but the presently preferred embodiment minimallynotes:

-   -   Management repeater port identification value;    -   Management repeater previous segment identification value; and    -   Amount of port network resource impact since power-up or last        load-balancing activation.

The preferred embodiment of the invention sorts this list of ports indescending order of network resource impact value. A list of segments onwhich to place the ports is also created. The algorithm proceeds,beginning with the port with the greatest network resource impact valueand processing the ports in descending order. The goal is to try to keepas many ports as possible on their previous segments in an intelligentfashion, while still obtaining a good overall load-distribution.

Two such key areas of the current implementation are:

-   -   Detecting when further changes in port-to-segment assignments        are not of sufficient benefit; and    -   Finding a well-chosen replacement port-segment assignment (if        any) to use in place of each obvious pairing which the basic        well-known selection algorithm (the “bin-packing” algorithm)        would make.

The replacement assignments in the latter case must be in range of thebasic selection algorithm's obvious port-segment assignment. For purposeof the discussion herein, in range means that the AlternatePort orAlternateSegment has some current decision-trigger value (for instance,individual port network resource impact value or segment total assignednetwork resource impact value) that is some deviationValue distance fromthe CandidatePort's or TargetSegment's value. The deviationValue couldbe a fixed value, a fixed percentage, the CandidatePort's percentage ofthe total network resource impact on all segments, or some otherintelligent consideration.

FIGS. 4A and 4B are flow diagrams showing a preferred implementation ofan intelligent port distribution algorithm according to the invention.The following pseudo code listing explains the algorithm in connectionwith FIG. 4A and FIG. 4B.

{ Find the next candidate port (104). This is the next port in thesorted list which has not already been marked as assigned by thisalgorithm. Sort the segments in ascending order (106) of current totalof the network resource impact of all ports placed on them by thealgorithm. Find the first segment with the least current networkresource impact total that is fully qualified as the target segment forthe CandidatePort (the restrictions for fully qualified vary from oneimplementation to another, but essentially indicate that there are noknown adverse effects to putting the given port on the given segment).Make this the TargetSegment (108). Check if the CandidatePort waspreviously on the TargetSegment (110). If so, assign it back to thatsame segment (124) and loop again above to process any further ports(122,102). Check whether the CandidatePort's network resource impactvalue is below a certain low threshold value, the SmallImpact threshold(112). If so, check whether the total network resource impact of allremaining unpiaced ports that previously were on the CandidatePort'ssame segment is below another certain low threshold value (126), theMaxAcceptableContribLevel threshold. If so, further changes in segmentassignments for these particular ports is not of sufficient benefit.Assign the CandidatePort and all of those other ports back to theirprevious segment (128) (this prevents moving small impacters who are notreally affecting that much of the network's resources). Then loop againabove to continue processing the ports on other segments (122, 102). Ifnot, continue processing the CandidatePort. Check whether anAlternateSegment exists for the CandidatePort (116). If the segment theCandidatePort was previously on is fully qualified with regard to theCandidatePort and is in range of the TargetSegment, an AlternateSegmentexists. Assign the CandidatePort to this AlternateSegment (132) and loopagain (122, 102) above to process any further ports. If none of theexceptions above were true, the TargetSegment is used. Look for anAlternatePort to assign to this TargetSegment in place of theCandidatePort. Proceeding in order through the list of sorted ports,check whether there is as yet a port not already placed by thisalgorithm that is in range to be used as an AlternatePort and for whichthe TargetSegment is fully qualified for placement (118). If anAlternatePort exists within range, assign it to the TargetSegmentinstead of the CandidatePort (134). Loop above again (122, 102), wherethe next CandidatePort is the same port as for this loop. If noAlternatePort exists within range, assign the CandidatePort to theTargetSegment (120) and loop above again (122, 102) to process anyfurther ports. }

The use of intelligent checking for opportunities to assign ports backto the segments they were previously on minimizes needlessly movingports, while at the same time obtaining a very good load for eachsegment. These intelligent checks are unique enhancements to the basic,well-known “bin-packing” selection algorithm.

Undo Prior Load-Balancing

With any user interface, there is the possibility of selecting andactivating a feature by mistake. This is true whether the user interfaceis a simple text console or a more sophisticated mouse-driven GraphicalUser Interface (GUI).

If a user were to accidentally activate the automatic load-balancingfeature, it would be very hard for them to later undo their mistake.This is because the same embedded intelligence that makes smartdecisions on the user's behalf also hides information to keep fromoverwhelming the unsophisticated user. Even if the user did know theexact full port-to-segment configuration prior to activating theautomatic load-balancing feature, it would be tedious for them to returnthe ports and segments to that configuration themselves. For example, inthe current embodiment of the invention, hundreds of ports may beinvolved.

The undo prior load-balancing feature takes information stored at aprior load-balancing activation and uses it to return ports to thatprior configuration. No action is taken on devices which were not knownto the agent at the time of that prior load-balancing.

The automatic load-balancing invention offers several advantages, forexample as follows:

First, it offers a decision-making process that provides intelligentautomatic determination of when a given load-balancing activationcurrently would not be beneficial, thereby keeping the user's networkfrom being unnecessarily disturbed when no real benefit would be gained.This user-friendly feature is enormously helpful to users who do notfully understand networks and who do not have any real sense of whennetwork conditions do or do not suggest taking an action.

Second, it offers an undo prior load-balancing process when users haveaccidentally activated a feature which could substantially change theirnetwork configurations. This user-friendly feature saves users fromtheir own mistakes, in a situation where it would otherwise be very hardfor them to undo such a mistake.

The preferred embodiment of the invention provides one level of undo,although other embodiments of the invention could have many levels ofundo. Each level of undo takes the user back to a next previousconfiguration, with the exception that newly added devices are notaffected. The invention stores the previous configuration, butalternative embodiments of the invention could also provide the userwith choices of default configurations, e.g. templates that provideconfigurations for different functions.

Third, it offers an extensive intelligent port-distribution algorithmthat improves the network load by moving the right ports to newsegments, while at the same time minimizing moving ports unnecessarily.With hundreds of possible ports to choose from in the maximumconfiguration allowed in the preferred embodiment of the invention, itwould be tedious for even a sophisticated user to choose the right portsto move. Unsophisticated users do not have enough knowledge about how anetwork works to begin to know how to choose whether to move ports. Thisuser-friendly feature benefits users who want better resourceavailability in their networks, but who lack the knowledge or theinclination to make changes themselves to improve this availability.Combined with the automatic determination of when a given instance offeature activation would not be beneficial, and the undo priorload-balancing features, it also lessens the possibility of users makingchoices that they may later regret.

Moreover, the intelligent port-distribution algorithm described hereinmerely requires multiple ports, and multiple segments to assign them to.It can be used when the intelligent network software agent does not haveaccess to any packet-forwarding address table information. Although aninternal packet-forwarding module is used in this embodiment of theinvention, it should be clear that with additional information fromother internal or external software mechanisms, or with minorconfiguration assistance from the user, other embodiments are possiblein which the packet-forwarding device is external to the hub stack andthe intelligent agent.

Although the invention is described herein with reference to thepreferred embodiment, one skilled in the art will readily appreciatethat other applications may be substituted for those set forth hereinwithout departing from the spirit and scope of the present invention.Accordingly, the invention should only be limited by the Claims includedbelow.

1. An automatic load-balancing apparatus for a segmented electronicnetwork, comprising: an intelligent port-distribution mechanism thatmoves ports to new segments to accomplish load-balancing; and a detectorthat determines when load-balancing would not be beneficial by weighingpotential benefit of an action against its consequences.
 2. Theapparatus of claim 1, said detector inhibiting load-balancing when acurrent load distribution is acceptable or when current network resourceimpact is so low that no real problems exist.
 3. The apparatus of claim2, wherein said detector makes an intelligent decision for a user whilepreventing needless network disruption.
 4. The apparatus of claim 1,further comprising: means for determining which ports are to be moved.5. The apparatus of claim 1, wherein said apparatus is adapted foroperation with a packet-forwarding device without requiring an interfaceto internal packet-forwarding support hardware.
 6. The apparatus ofclaim 1, wherein said apparatus is adapted for operation with anexternal packet-forwarding device.
 7. The apparatus of claim 1, whereinsaid apparatus is adapted for operation without special knowledge by auser of said apparatus, the apparatus environment, or electronicnetworks in general.
 8. The apparatus of claim 1, wherein at least aportion of said mechanism is adapted to reside remote from saidapparatus within said network at a management location.
 9. An automaticload-balancing apparatus for a segmented electronic network, comprising:an intelligent port-distribution mechanism that moves ports to newsegments to accomplish load-balancing while minimizing the unnecessarymoving of ports by keeping as many ports as possible on previoussegments; and an undo mechanism for undoing a prior load-balancing. 10.The apparatus of claim 9, wherein said undo mechanism takes informationstored during a prior load-balancing activation and uses it to returnports to a previous configuration.
 11. The apparatus of claim 10,wherein no action is taken by said undo mechanism on devices that werenot known at the time of said prior load-balancing.
 12. The apparatus ofclaim 10, wherein said undo mechanism provides one or more levels ofundo.
 13. The apparatus of claim 10, further comprising: a detector forintelligent automatic determination of when a given load-balancingactivation currently would not be beneficial.
 14. The apparatus of claim13, said detector inhibiting load-balancing when a current loaddistribution is acceptable or when current network resource impact is solow that no real problems exist.
 15. The apparatus of claim 14, whereinsaid detector weighs potential benefit of an action against itsconsequences, and makes an intelligent decision for a user whilepreventing needless network disruption.
 16. The apparatus of claim 9,further comprising: means for determining which ports are to be moved.17. The apparatus of claim 9, wherein said apparatus is adapted foroperation with a packet-forwarding device without requiring an interfaceto internal packet-forwarding support hardware.
 18. The apparatus ofclaim 9, wherein said apparatus is adapted for operation with anexternal packet-forwarding device.
 19. The apparatus of claim 9, whereinsaid apparatus is adapted for operation without special knowledge by auser of said apparatus, the apparatus environment, or electronicnetworks in general.
 20. The apparatus of claim 9, wherein at least aportion of said mechanism is adapted to reside remote from saidapparatus within said network at a management location.
 21. An automaticload-balancing apparatus for a segmented electronic network, comprising:an intelligent port-distribution mechanism that moves ports to newsegments to accomplish load-balancing, wherein the mechanism weighspotential benefit of an action against its consequences.
 22. Theapparatus of claim 21, wherein said mechanism first collects a snapshotof information about all network ports to be considered forredistribution.
 23. The apparatus of claim 22, wherein said snapshotfurther comprises any of the following: a management repeater portidentification value; a management repeater previous segmentidentification value; and an amount of port network resource impactsince power-up or last load-balancing activation.
 24. The apparatus ofclaim 22, wherein said mechanism makes an intelligent decision for auser while preventing needless network disruption.
 25. The apparatus ofclaim 22, wherein said mechanism keeps as many ports as possible on aprevious segment while still obtaining a good overall load-distribution.26. The apparatus of claim 22, wherein said mechanism detects whenfurther changes in port-to-segment assignments is not of benefit. 27.The apparatus of claim 22, wherein said mechanism finds a replacementport-segment assignment in range of, and uses in place of, a pairingthat would be chosen by a basic “bin-packing” selection criteria forport-segment assignment.
 28. The apparatus of claim 27, wherein anassignment is in range when an alternate port or alternate segment has acurrent decision-trigger value that is a deviation value distance from acandidate port or target segment value.
 29. The apparatus of claim 28,wherein said deviation value comprises one or more of the following: afixed value; a fixed percentage; a candidate port percentage of totaldecision criteria value on all segments; an individual port decisioncriteria value; or a segment total assigned decision criteria value. 30.The apparatus of claim 21, further comprising: means for determiningwhich ports are to be moved.
 31. The apparatus of claim 21, wherein saidapparatus is adapted for operation with a packet-forwarding devicewithout requiring an interface to internal packet-forwarding supporthardware.
 32. The apparatus of claim 21, wherein said apparatus isadapted for operation with an external packet-forwarding device.
 33. Theapparatus of claim 21, wherein said apparatus is adapted for operationwithout special knowledge by a user of said apparatus, the apparatusenvironment, or electronic networks in general.
 34. The apparatus ofclaim 21, wherein at least a portion of said mechanism is adapted toreside remote from said apparatus within said network at a managementlocation.
 35. An automatic load-balancing method for a segmentedelectronic network, comprising the steps of: providing an intelligentport-distribution mechanism that moves ports to new segments toaccomplish load-balancing; and determining when load-balancing would notbe beneficial by weighing potential benefit of an action against itsconsequences.
 36. The method of claim 35, further comprising the stepof: inhibiting load-balancing when a current load distribution isacceptable or when current network resource impact is so low that noreal problems exist.
 37. The method of claim 36, further comprisingmaking an intelligent decision for a user while preventing needlessnetwork disruption.
 38. The method of claim 35, further comprising thestep of: determining which ports are to be moved.
 39. The method ofclaim 35, wherein said method is adapted for operation with apacket-forwarding device without requiring an interface to internalpacket-forwarding support hardware.
 40. The method of claim 35, whereinsaid method is adapted for operation with an external packet-forwardingdevice.
 41. The method of claim 35, wherein said method is adapted foroperation without special knowledge by a user of said method, the methodenvironment, or electronic networks in general.
 42. The method of claim35, wherein at least a portion of said mechanism is adapted to resideremote from devices upon which said method operates within said networkat a management location.
 43. An automatic load-balancing method for asegmented electronic network, comprising the steps of: providing anintelligent port-distribution mechanism that moves ports to new segmentsto accomplish load-balancing while minimizing the unnecessary moving ofports by keeping as many ports as possible on previous segments; andproviding a mechanism for undoing a prior load-balancing.
 44. The methodof claim 43, further comprising the steps of: taking information storedduring a prior load-balancing activation; and using such information toreturn ports to a previous configuration.
 45. The method of claim 44,wherein no action is taken by said undo mechanism on devices that werenot known at the time of said prior load-balancing.
 46. The method ofclaim 44, wherein said undo mechanism provides one or more levels ofundo.
 47. The method of claim 44, further comprising the step of:determining when a given load-balancing activation currently would notbe beneficial.
 48. The method of claim 47, further comprising the stepof: inhibiting load-balancing when a current load distribution isacceptable or when current network resource impact is so low that noreal problems exist.
 49. The method of claim 48, further comprising thesteps of: weighing potential benefit of an action against itsconsequences; and making an intelligent decision for a user whilepreventing needless network disruption.
 50. The method of claim 43,further comprising the step of: determining which ports are to be moved.51. The method of claim 43, wherein said method is adapted for operationwith a packet-forwarding device without requiring an interface tointernal packet-forwarding support hardware.
 52. The method of claim 43,wherein said method is adapted for operation with an externalpacket-forwarding device.
 53. The method of claim 43, wherein saidmethod is adapted for operation without special knowledge by a user ofsaid method, the method environment, or electronic networks in general.54. The method of claim 43, wherein at least a portion of said mechanismis adapted to reside remote from devices upon which said method operateswithin said network at a management location.
 55. An automaticload-balancing method for a segmented electronic network, comprising thesteps of: providing an intelligent port-distribution mechanism; andmoving, using the port-distribution mechanism, ports to new segments toaccomplish load-balancing, wherein the mechanism weighs potentialbenefit of an action against its consequences.
 56. The method of claim55, further comprising the step of: collecting a snapshot of informationabout all network ports to be considered for redistribution.
 57. Themethod of claim 56, wherein said snapshot comprises any of thefollowing: a management repeater port identification value; a managementrepeater previous segment identification value; and an amount of portnetwork resource impact since power-up or last load-balancingactivation.
 58. The method of claim 55, further comprising making anintelligent decision for a user while preventing needless networkdisruption.
 59. The method of claim 55, further comprising the step of:keeping as many ports as possible on a previous segment while stillobtaining a good overall load-distribution.
 60. The method of claim 55,further comprising the step of: detecting when further changes inport-to-segment assignments is not of benefit.
 61. The method of claim55, further comprising the step of: finding a replacement port-segmentassignment in range of, and using in place of, a pairing arising frombasic selection criteria for port-segment assignment.
 62. The method ofclaim 61, further comprising the step of: determining that an assignmentis in range when an alternate port or alternate segment has a currentdecision-trigger value that is a deviation-value distance from acandidate port or target segment value.
 63. The method of claim 62,wherein said deviation-value comprises one or more of the following: afixed value; a fixed percentage; a candidate port percentage of totaldecision criteria value on all segments; an individual port decisioncriteria value; or a segment total assigned decision criteria value. 64.The method of claim 55, further comprising the step of: determiningwhich ports are to be moved.
 65. The method of claim 55, wherein saidmethod is adapted for operation with a packet-forwarding device withoutrequiring an interface to internal packet-forwarding support hardware.66. The method of claim 55, wherein said method is adapted for operationwith an external packet-forwarding device.
 67. The method of claim 55,wherein said method is adapted for operation without special knowledgeby a user of said method, the method environment, or electronic networksin general.
 68. The method of claim 55, wherein at least a portion ofsaid mechanism is adapted to reside remote from devices upon which saidmethod operates within said network at a management location.
 69. Anintelligent port-distribution method that moves ports to new segments toaccomplish load-balancing in a segmented electronic network, comprisingthe steps of: collecting a snapshot of information about all networkports to be considered for redistribution; sorting said ports indescending order of network resource impact value; finding the nextcandidate port which is the next port among said sorted ports that hasnot already been assigned; sorting segments in ascending order ofcurrent total of network resource impact of all ports placed on them;finding the first segment with a least current network resource impacttotal that is fully qualified as the target segment for a candidateport; checking if said candidate port was previously on the targetsegment and, if so, assigning said candidate port back to that samesegment; and processing any further ports.
 70. The method of claim 69,further comprising the steps of: checking whether a candidate portdecision criteria value is below a predetermined low threshold valueand, if so, checking whether a total network resource impact of allremaining unplaced ports that previously were on said candidate port'ssame segment is below a maximum acceptable contribution level thresholdand, if so, then determining that further changes in port-to-segmentassignments is not of sufficient benefit; assigning said candidate portand all of said other ports back to that previous segment; andcontinuing processing said ports on other segments and, if not,continuing processing said candidate port.
 71. The method of claim 70,further comprising the steps of: checking whether an alternate segmentexists for said candidate port and, if the segment that said candidateport was previously on is fully qualified with regard to said candidateport and is in range of said target segment, then determining that analternate segment exists; assigning said candidate port to saidalternate segment; processing any further ports; and using said targetsegment if no exception is true.
 72. The method of claim 71, furthercomprising the steps of: looking for an alternate port to assign to saidtarget segment in place of said candidate port; proceeding in orderthrough said list of sorted ports; checking whether there is a port thatis not already placed, but that is in range, and that previously residedon said target segment, which can be used as an alternate port, and forwhich said target segment is fully qualified for placement and, if analternate port exists within range; assigning said port to said targetsegment instead of said candidate port; and processing any furtherports, and if no alternate port exists within range, assigning saidcandidate port to said target segment; and processing any further ports.73. The method of claim 69, further comprising the step of: determiningwhich ports are to be moved.
 74. The method of claim 69, wherein saidmethod is adapted for operation with a packet-forwarding device withoutrequiring an interface to internal packet-forwarding support hardware.75. The method of claim 69, wherein said method is adapted for operationwith an external packet-forwarding device.
 76. The method of claim 69,wherein said method is adapted for operation without special knowledgeby a user of said method, the method environment, or electronic networksin general.
 77. The method of claim 69, wherein at least a portion ofsaid mechanism is adapted to reside remote from devices upon which saidmethod operates within said network at a management location.
 78. Amethod for moving ports to new segments in a network for load balancing,comprising: collecting information about the ports and segments in thenetwork, the information including network resource impact value; andassigning ports to new segments based on the information whileminimizing the unnecessary moving of ports by keeping as many ports aspossible on previous segments.
 79. The method of claim 78, whereincollecting information about the ports and segments includes collectingnetwork resource impact values for the ports.
 80. The method of claim78, wherein collecting information about the ports and segments includescollecting total network resource impact values for segments.
 81. Themethod of claim 78, wherein assigning ports to new segments includesassigning ports based on past history of the ports.
 82. The method ofclaim 78, further comprising: determining which of the ports are to bemoved.
 83. The method of claim 78, further comprising: determining whenload balancing would not be beneficial.
 84. The method of claim 78,further comprising: undoing a previous assignment of the ports to newsegments.